(Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Earning per share reconciliation
Net (loss)	$ (30,338)	$ (32,296)	$ (28,717)	$ (7,587)	$ (10,409)	$ 12,200	$ (91,351)	$ (5,796)
Weighted-average common shares outstanding (in shares)	79,200			78,700			78,928	78,525
(Loss) per share, basic (in dollars per share)	$ (0.38)			$ (0.10)			$ (1.16)	$ (0.07)
Effect of dilutive securities (in shares)	0			0			0	0
Weighted-average common shares outstanding, assuming dilution (in shares)	79,200			78,700			78,928	78,525
(Loss) per share, diluted (in dollars per share)	$ (0.38)			$ (0.10)			$ (1.16)	$ (0.07)
Outstanding anti-dilutive stock options and RSUs (in shares)	5,953			6,119			5,923	6,380
Stock options
Earning per share reconciliation
Weighted-average effect of dilutive securities (in shares)	0			0			0	0
RSUs
Earning per share reconciliation
Weighted-average effect of dilutive securities (in shares)	0			0			0	0